Groundbreaking London research is shedding light on a disturbing behaviour often affecting teens - deliberately cutting or burning themselves - that could have its roots in the way their brains process pain.

Cutting is a form of deliberate self-harm celebrities like Angelina Jolie and Demi Lovato have admitted to doing, which has also been featured in films like 'Black Swan.'

Dr. Elizabeth Osuch, a psychiatrist at the Lawson Health Research Institute, wanted to know what's behind the behaviour known clinically as non-suicidal self-injury.

"People who engage in this behaviour do it repetitively and they seem to experience a sense of relief from it, which is quite strange to those of us who don't do this, because, you know if I cut myself or burn myself I say, 'I'm not going to do that again.'"

For her study, a group of people who self-injured and a control group were asked to apply ice water to their skin, which is painful, but not harmful, and what what she found in the brain scans was astonishing.

Looking at regions of the brain on a scan she explains "These are very much reward-processing regions of the brain. And so the more these regions were activated, the more relief they experienced in response to the painful stimulus."

Cutting and burning are very troubling and very common. According to some estimates upwards of 40 per cent of kids aged 12 to 15 have tried these behaviours and some six per cent do them routinely.

The research suggests a biological component for a behaviour that's been difficult to understand.

"Some people do engage in this behaviour for what seems to be purposes related to others around them. But the vast majority of them actually engage in the behaviour to change their own mental state. So, this is further a demonstration that there is something in their brains that the behaviour is probably attempting to correct."

The research offers the possibility that treatments targeting certain brain regions could offer help.